Fluid motor



May 6, 1941. Gi. A; WAHLMARK f 2,241,046

FLUID MOTOR Fled Feb. '7, 1938 5 Sheets-Sheet 1 Nn ,Mb ms mm .May 5, 1941 A. wAHLMARK 2,241,046

' FLUID MOTOR Filed Feb. 7, 19:58 5 sheets-sheet 2 l f: f SAM.. f,

MaI/(6, 1941 l G. fA. WAHLMARK l 2,241,046

FLUID MOTOR Filed Feb; 7, 195s 5 sheets-sheet s G. A. WAHLMA'RK May 6, 1941.v

FLUID MOTOR Filed Feb. '7. 193s 5 sheets-sheet 4 MayV 6, 1941.

' G. A. WAHLMARK i FLUID MoToR Filed Feb 7, 1938 5 sheets-sheet 5 Planted myc, 1941 UNITED STATES-:PATENT orticaA ...ifo

' Gu'nm; ryay 'z v1sz.azu;cexlliifiiri;uit9 tis Application icl. iai- 119) 0 17 Claims.

The invention relates 'to a fluid motor; more particularly, to one operable at a plurality of speeds, it being the general object of the inven- 7 tion to provide a new and improved multi-speed motor. r

.Another object is to provide a. two-speed fluid motor of new and simpliiied construction and particularly adapted for use with a feed andl rapid traverse drive for machine tools.

Other objects include the provision of a twospeed uid motor of improved construction capable of producing a high torque at a slow speed r for feed purposes and a high speed for rapid traverse; enabling the use of a constant displacement wobbler for the motor shaft; and having low speed and. high speed pistondevices grouped annularly about the drive shaft with a speed control valve positionef intermediate the shaft and piston devices so as to provide a compact small sized unit.

A further object is to provide in such a motor a new and improvedr wobble plate construction for connecting the pistons to drive the motor 'A further object is -to provide such ainotor having an adjustable wobble plate construction to permit offurther adjustment of the speeds imparted. to the motor shaft by the diierent sets of pistons.

Other objects will become readily apparent from the following detailed description taken in connection with the accompanying drawings. in

which: i

Fig. 1 is a longitudinal central section through a preferred form of the invention valong the line `II ofFlg. 5.

Fig. 2 is a fragmentary 2-2 of'Fig.` 4.

Fig 3 is a fragmentary plan view ofthe left end of the motor shaft looking in the direction of the arrows 3-3 of Fig. 1.

section along the Yline Fig. 4 isa transverse section along the line 4-4 of Fig. 1 with portions broken away for. Vthe sake of clearness.

Fig. 5 is a view partly in sectionV generally along the line I-I' of Fig. 1.

Flg.'6 is a longitudinal section ified form of the invention, portions thereof -being somewhat diagrammatic and in different planes to make the iluid connections clearer.

Fig. 'I is 'a fragmentary plan view of the left emi of the motor shaft looking in the direction Fig. 8 is a transverse section approximately through a modalong the line l-l of Fig. 6 with portions broken away to illustrate certain ports more clearly.

Fig. 9 is a transverse section approximatelyy along the line 9 9 of Fig. 6.

Fig. 10 is a view through another modied form of the invention,

Partly in v longitudinal central section.

Although the invention is susceptible of embodiment in many different/forms, there is shown in the drawings and herein described in detail three forms selected for the purpose of dsclosing the principles of the invention. It is contemplated that various-modifications and alternative constructions may `be made by; those skilled inthe art without departing from the spirit and scope of the appended claims.

. In the form illustrated in Figs. 1 to 5 of the drawings, the' inventionis embodied 'in a twospeed iiuid motor which comprises generally a casing I0 within whichlis housed uid handling The casing III as illustrated herein comprise a plurality of sections 20, 2l. 22, 23, and 24 which are secured together to form a unit by means of a plurality of bolts 25 extending through the sections 24, 23, 22, and 2li and into threaded engagement with the section 2l. Section 20 constitutes a cylinder block and has a thicker'porvtion. 20' formed with a plurality of bores 26, herein nine in number (see Figf4) disposed longitudinally of thecaslng and arranged annularly about the shaft I2. Casing section 22 is .in the form of a port 4plate and abuts against.

the head or lei't hand end (Fig. 1) of the cylinlder block and cooperates therewith to complete the motor block. The port plate 22 is formed withv a plurality of recesses' 21 larger in diameter than the bores 26 and registering therewith to complete the head ends of the cylinders. Opening -to each of the recesses 21 is a cylinder port 28 which, as best seen in Fig. 5. issomewhat elliptical inA shape, being formed by three apertures approximating the. shape of.' an ellipse. Thecylinder block 2l and the port plate 22 are 29 inserted through a central aperture formed "in the'block 20 (by a stepped bore 30). and

threaded into the port plate 22.

nular relief grooves 33 are: provided in the bushings intermediate their ends. The bushings 33 are secured in the bores 26 by means of a collar 34 which is screw threaded in the adjacent end of the portion of the casing section 20 and has a ange34 engaging flanges 33" on the bushings to clamp them against the adjacent end of the section 20. The two series or sets of pistons are selectively operable 'to drive the shaft I2 at different speeds through the. agency cf the conversion means I3 in a manner hereinafter more fully described. .4

The conversion means I3 is herein illustrated in the form of a wobble plate 35 secured to the shaft I2 by means of a key 36 and against a shoulder 36 and provided with an annular flange 35 vand a cylindrical surface 35", against which one race 38 of a ball bearing of improved construction is mounted. ball bearing has a series of balls 31 positioned intermediate races 38 and 39, which carry a combination thrust'and radial load in converting reciprocatory'movement of the pistons into rotary movement of the shaft I2. The race 39 has a fiat surface 39 which engages the adjacent ends of thepistons 32.4 The piston ends 32 are conical in shape so as to pro-'- vide a line contact with the race surface 39'. A collar is pressed onto the surface 35" and has a projecting flange 45 which serves to hold the race 3S in assembled relation. The shaft I2 is supported at one end in a needle bearing 40,

' positioned in a recess 28' in the sleeve y2i), and

' secured together bymeans of a shouldered sleeve the port plate 22 so as to form a valve chamber I6' therebetween. VInlet passage I4 communicates with the outer edge of the valve chamber I6' by means of a plurality of arcuate ports 50 l(see Figs. 1 and 5) and an intermediate annular pori'l 5|. Exhaust passage I5I communicates with a. plurality of arcuate ports 52 through intermediate ports 53, thearcuate ports 52 communicating with the valve chamber I6' at points spaced inwardly from the periphery thereof, as shown most clearly in Fig. `1. 'I'he inlet ports 50 and the exhaust ports 52 are..formedencentrically with the shaft I2 as are also the cylinder ports 28.

'I'he cylinder ports are herein controlled by means of thevalve I6 which is adapted to effect the opening and closing of the ports and their alternate connection to the inner and outer portions of the valve chamber I5' in timed relation with the reciprocation of the pistons in a manner is supported at its other end by a ball bearing plied with a predetermined volume of fluid underpressure. Pistons 32, of substantially smaller cross section area, may be referred to ashigh speed pistons,.and when operated by an equal volume of fluid under pressure are effective Vto rotate the shaft I2 at a higher speed. The means for supplyinguid to actuate the low speed and high speed pistons to attain these results will now be described.

The passage I4, passage I5, and valve SIG, to-4 gether with the ports for conducting fluid to and from the cylinder ports 28, are similar to those illustrated and described in my prior U. S. Letobtaining amaximum period of port opening and rapid opening and closing of the ports. The valve I6 is circular ln form and is mounted by means of a ball bearing 55 on a stud 56 formed eccentrically (see Figs. 1 and 3) on the inner end of the shaft I2 and projecting into the space between the port plate 22 and the section 24.

'I'he faces of the valve I6 are ground so as to have a uid-tight sliding iit with the adjacent faces of the port plate 22 and the section 24. 'I'he valve is most readily pictured as .a wheel having a hub 162 and a rim 63 secured tothe hub by a plurality of spokes 64 of reduced thickness so as to form annular recesses- 55 and 85 interconnected by means of circular openings 66 formed between the spokes; The recess 65' is so disposed that it is always in communication with the arcuate exhaust ports 52 and is of such width that in any position of the valve several of the cylinder ports 28 open in whole or in part thereto.. The. rim 63 has a radial thickness slightly greater than the width of a port 28, so that in any position of the valve I6, a plurality of ports 23 are disposed in whole or in part outwardly of the valve I6 so as to communicate with the peripheral portion of the valve chamber I6' which issupplied by the inlet ports 50. Thus, the rim 63 of the valve, during rotation of the shaft I2 and the simultaneous orbital movement of the valve, connects the cylinder ports 28 with the inlet ports 5|!l during the intake strokes of the pistons and connects'the cylinder ports 28 with the outlet ports 52 during the exhaust strokes of the pistons. Furthermore, when a piston is at one end or the other of its stroke, the-rim 63 `closes the corresponding cylinder port 28. In the operationof the valve, the movement of the rim 63 with respect to thev cylinder ports 28 is such that the ports are opened and closed very rapidly lbecause the eccentric stud 56 is then moving more Idirectly toward or away from the particular cylinder port.

' In the form of the invention chosen for purposes of disclosure', it is contemplated that the low speed pistons 3| will normally function to drive the shaft I2, the high speed pistons 32 then serving as piston rods for the pistons 3| `and connecting them to the race 39 of the wobble ters Patent No. 2,190,812 dated February 20,`

the wobble plate.

The operationv of the shaft I2 at a' relatively higher speed by the pistons 32 is effected by establishing lcommunication between the cylinder vports 28 and the cylinder bores 28 at points located to the right (Figs. 1 and 2) of the pistons 3|, the pistons 3| .then' remaining stationary Y against projections vlvformed on the port plate 22 and functioning as the head yends of the cylinders in which the pistons 32 then reciprocate. As illustrated'herein, communication is established intermediate the cylinder ports-23 and the,`

cylinder bores 26 by means of a plurality of ports 1| (Figs. 2` and 4) extending longitudinally adjof said'chamber (Figs. 1 and 2) by means of a coiled spring positioned intermediate a shoulder 1,6 on the valve and the collar 34. In -this position of the valve 14, uid cannot now from the ports1| through thevalve chamber 12 and .into the port 13, since the valve then blocks communication between the ports, as illustrated in Fig. 2. ToV establish communication between the ports 1|-and 13, the valve is provided with a plurality of longitudinally extending recesses 11,

' one for each piston and cylinder device, so lo- 'enlarged 'portions |21 at the head ends located in a port plate |22. Conically surfaced ends |3| ofthe large pistons bear against one race |33 of the wobblerbearlng which race is providedl with a fiat surface |38'. A second series of smaller pistons |32 are reciprocably mounted in bores |28 positioned radially inward from the bores |23. These pistons have conically surfaced endsv l|32' also bearing against the flat face |38' of the' wobbler bearing race |38. The head ends of the cylinders |23' connect with recesses |21' in the port plate |22 which in turn connect with cylinder ports |28.

1n thisformL of the invention, it is contemplated that the pistons |3| and the pistons |32 will be'utilized simultaneously to' drivethe shaft l |2 at a low speed and that, alternatively, the pistons |32 alone will be used to drive the shaft '|2 at a higher speed. The c'ontrol means for selectcated in the valve 14 that when the valve is moved to the right (Figs. 1 and 2) and up against' the adjacent collar 34, the `recesses 11 'connect the ports 1| and 13. In order to permit proper' operation of the valve, it is held against rotary movement by means of a pin 13 (Fig. 1) which is 'carried by the valve and slides in a bore 19 formed in the collar 34. vFurthermore,the collar is preferably provided with one or more ports 80 so that pressure will not build up in the valve chamber 12 and prevent operation of the valve. Since the valve 14 (in'its low speed position as i1- iustrated in Fig. 2) uncovers-the ports 13, the rod ends of the bores 26 are relieved during operation of the low speed pistons through the ports 13,

chamber 12 and ports 80.

Means is preferably provided for operating the d valve 14 by uid under pressure, and this is particularly true when the motor is intended for use in connection with the feed traverse mechanism of a machine tool or in a circuit such as No. 2,214,390dated September 10. 1940. Thus,

Athat disclosed in my prior U. S. Letters Patent the left hand end of the valve 14 has apro- Y jecting portion 14"which serves to' space the valve away from the end of the valve chamber 12 formed by a flange 29 on the sleeve 29. 'A fluid port 8| isprovided for conducting-fluid l under pressureto this end of the valve chamber,

the adjacent end vof the valve then functioning as a pistonywhich is movable by the fluid to shift' the valve from its left hand or low speed position to its right hand or high speed position. When thesupply of pressure duid is disconing one set of pistons or theother for driving the shaft I2 is in certain respects quite similar t0 that illustrated in Figs.. 1. t0 5. Thus, as illllsmeans of the longitudinal recesses 11 of the valve. Since in this form'of the invention the cylinder ports |248 connect directly with the small cylinders, the valve 14 is in its left hand position when the large pistons `I 3| and the small pistons |32 are operative together to drive the shaft I2 at a slow speed. By admitting uid to the left hand end of the valve 14.from a suitable pressure source by means of a port 8|, the valve is moved toward the right so as to close oi communication between the Sports |.1| and |13 and render the pistons |32 alone operable to drive the shaft I2. In this position 'of the valve 1E, the recesses 11 connect the ports |1| to the right hand end of the valve chamber 12 so as to relieve the headA ends |21 of the large ylinders through the relief ports 80 in the collar |313.

In the form of the invention illustrated in Fig.

10, the left hand portion shown in elevation is identical with the similar portion of lthe form illustrated in Figs. 1 to 5. 'Ihis form' of the inventlon diiers principally in that the conversion o a key 286 which ls slidable longitudinally in a.

suitable keyway 281 in the shaft-and has an inclined end or cam surface 286' which 'en- Thus, by moving the key 286 toward the left in v Fig. 10 longitudinally of the shaft (by` means nected, the valve is returned to its low speed position by the spring 15.

In the formof the invention illustratedqirn Figs 6. 7, 8, and 9, many of the parts are essentially the same as those illustrated in Figs. 1 to 5 and aresimilarly numbered. -In this second form of the invention, the fluid handling mechanism comprises a first series of large pistons |3| reciprocably mounted in cylinder bores |28 whichhave gages a roller 28,8 which is rotatably mounted on Ia -pin 288 secured to the wobble plate 235.

hereinafterV mbre .fully described),`the wobble plate may be positively tiltedaround thepivot pin 285. When the key is moved in the opposite direction or toward the right, as shown in Fig. 10, thewobble plate may tip back in a clockwise direction toreduce the stroke of the pistons. Such movement of the wobble plate is insured by placing the pivot pin 285 below the axis of .the

Aagainst the cam 286.

As illustrated herein, the means for moving the key 296 longitudinally of the shaft comprises a screw device 290 rotatably mounted in a housing 2|0' secured =to the casing 2li). The'screw device is prefer-ably squared at 290 to facilitate operation thereof. A nut 29| is screw-threaded onto the screw device 2,90 and has an outer spherical surface 29 positioned in a corresponding, spherical socket 292 Aformed in one end of a lever 293, the other end of which has a sphericalsurface293f engaging `in a bore 294 of a sleeve 294 which surrounds the shaftA 2|2 land is slldable longitudinally 'thereof in a tubular portion 22|'l of a casing part 22|, The sleeve 294 is connected to the key 286 by means of a plurality of balls 295 'which cooperate with a portion 294" of the sleeve 294 and an annular ring 236 formed integrally with the key 286 to form a ball bearing, the portions 294" and 286" serving as outerand inner races of the bearing. Intermediate its ends, the lever 293 has a spherical'surface 293" which bears against the inner surface of an annular bushing 296 supported in the casing 2| 0 so as to permit the lever 293l to pivot in the bushing 296 and as well to move longitudinally therein.

As mentioned hereinbefore, the remainder of' this form of the invention is shown as identical wi-th that shown in Figs. 1 to 5, although the conversion means 2|3 is equally well adapted for .use with other forms of the invention, such, 'for `supported in a portion of the casing par.t 2|i.

Furthermore, the wobble plate is formed in part by a. ball bearing consistingl of a series of balls 31 positioned intermediate races 38 and ,39, the race 39 having a flat surface 39 engaging the adjacent conical ends 32 of the pistons.

It'is believed readily apparent I that the inven- .vaive mechanism for controlling the inlet and' outlet of `fluid to the first series of cylinders, a

tion in the formsdisclosed herein provides a simple and compact mul-ti-speed motor. When supplied with a constant volume of fluid under pressure, 'the shaft may be driven at a relatively high speed by using only the smaller pistons, whereas to drivethe shaft at a relatively slow speed, the large pistons may be used, or the .large pistons together with the small pistons, in

the form illustrated in Figs. 6 to 9. By locating the control valve fl4'within the cylinder block,l

a compact and efficient control is obtained. Furthermore, lthe'improved bearing construction for the wobbler and the line contact between the pistons and the adjacent bearing race reduce lthe wear and provide for a long life of the parts.

`If desired, Vthe wobble plate may be madevadjustable ,as illustrated in Fig. 10, in which case the two speeds imparted to the shaft by the -pistons may be changed. l

l claim as my invention: l.- A two-speed fluid motor comprising, in combination,A a casing, a plurality of low speed pistons, a plurality .of highspeed pistons, a driven shaft, means including an adjustable wobble plate connecting the pistons to drive said shaft,

g means for conducting fluid to and from said cylinders includinga control device operable in` one position to eilect operation of the low speed pistons and operable in another position to effect operation of said high speedpistcns, means for actuating said control device, and means for ad- Justing the wobble plate. l y

2. AV uid motor comprising, in combination,

a casing, a first series of piston and cylinder devices in said casing, a second series of smaller piston devices positioned in reduced portions of vthe cylinders of said first series, a driven shaft,

means forming an adjustable driving connection between the pistons of said devices and the shaft adjustable to vary the stroke of the pistons, a

tioned piston, a driven shaft, means formingA a driving connection between said second piston and the drivenshaft, means for controlling the inlet and outlet of fluid to the end of said lcylinder occupied by said first piston to effect,

rotation of said shaft at onel speed, and means including a valve device fordirectingiluid to the other end of said cylinder so that the fluid actuates said second piston and drivessaid shaft at a higher speed. v

4. A two-speed uid motor comprising, in combination, a casing, a cylinder therein, a piston slidably mounted in saidcylinder, a second piston of smaller size slidablymounted in said cylinder and selectively 4operable as a piston vor as a rod for said first mentioned piston, a driven shaft, means forming a driving connection between sad second piston and the driven shaft, a valve mechanism for controlling the inlet and outlet of fluid to the end of said cylinder occupied by said rst piston, and means including a valve device for connecting the -two ends of said cylinder so that the fluid actuates said second piston. l

' 5. A two-speed fluid motor comprising, in combination, a casing, a cylinder therein, a piston slidably mounted in said cylinder, a. second piston of smaller size slidably mounted in said.

.uid actuates said second piston.

6. A two-speed fluid motor comprising, in combination, a casing, a drivenk shaft rotatably mounted'therein, a series of parallel cylinders arranged annularly about said shaft, pistons reciprocable in the head ends of-said cylinders, supplemental pistons of a smaller size recip- 4rocable in said cylinders and extending from the opposite ends thereof, a valv'e driven by said shaft forcontrolling the inlet and outlet of fluid to and from the head ends of said cylinders, means for connecting the head ends of said cylinders with the opposite ends thereof for transferring fluid therebetween and an annular valve device operable in one Vposition to close combination, a casingUa Atta-:nose

said connecting means ,and render the large relatively movable races, one of which has a flat pistons effective to drive said shaft and operable in another position to open said connecting means and render said smallerpistons effective to drive the shaft, and means for moving said valve device.

7.'A two-speed fluid motor comprising, in driven shaft rotatably mounted therein, a series of parallel cylinders arranged annularly about said shaft, pistons reciprocable in the head ends of ysaid cylinders,

supplemental pistons of a smaller size recip-V rocable in said cylinders and extending from the opposite ends thereof, valve means'for controlling the inlet and outlet of vfluid to and fromthe head ends of said cylinders, means for connectend surface engaging vwith a line contact the adjacent conical ends of said high speed pistons,

` and control means for changing the speed of said driven shaft by rendering onel set of pistons Vor the other effective to operate said wobble plate comprising means for alternatively connecting said cylinder ports to the opposite ends of the ing the head endsV of said cylinders with the opposite ends thereof for transferringvfluid therebetween, a shiftable lvalve device operable in one position to close saidconnecting means and render the large pistons effective to drive saidshaft and operable in another position to open said connecting `means and render said smaller' pistons effective to drivesaid shaft, means for moving -said valve device into said first mentioned position, and pressure fluid operated means for moving said valve device into said cylinders including an annular valve device surrounding said shaft and within the cylinder annulus operable in one position to close said connecting means and render the low speed pistons effective to drive the shaft and operable in another position to open said connecting means and render the high speed pistons effective to drive the shaft, meansfor shifting said..valve device and means for relieving the pressure in the rod ends of said cylinders when the motor is oper- A ating at low speed.

mounted therein, a series of parallel cylinders arranged annularly about said' shaft, large pistons reciprocable in the head ends of said cylinders, supplemental pistons of a smaller size reciprocable in said cylinders and extending from the opposite ends thereof,4 al valve device driven by said shaft for controlling the inlet and out-'1 let of fluid to and from the head ends of said cylinders, means for connecting the head ends of said cylinders with the opposite ends thereof for transferring iiuid therebetween, an annular valve device surrounding said shaft operable in one position to close said connecting' means and render the large pistons effective to drive said shaft and 'operable in another position to open said connecting means and render said smaller 9. In a device of the character described, in

combination, a casing having a plurality of an-` nularly arranged cylinders therein, a port plate having recesses forming the head ends of said cylindersand provided with a port for each cylinder, a ring valve slidably mounted for eccentric movement on said port plate and over the ends of said ports, inlet andexhaust ports in said casing communicating with a valve chamyber enclosing said valve, saidi'nlet ports opening into the valve chamberradially outwardly of the cylinder ports and the outlet ports open- 10. In-a device of thejcharacter described, in

combination, a casing having a plurality of .cyl-

inders therein, a port for the head endof each cylinder and a valve chamber, a valve slidably mounted in the valve chamber for eccentric Y movement over the ends of said ports, inlet ports opening into the valve chamber to one side of the valve chamber tothe other side of said cylinder ports, a driven shaft rotatably mounted in the casing, an eccentric means thereon for operating said valve, aplurality of large pistons in one end of said cylinders', a-series of pistons of smaller diameter slidably mounted in the other `endsof said cylinders and selectively operable to drive` the shaft, means forming a driving connection Ibetween -said smaller fsized pistons and said shaft, and control means for changing the speed of said driven lshaft by rendering one set of pistons or the other effective to operate said shaft comprising meansifor alternatively connecting said cylinder ports to the opposite ends of the cylinders including a valve device operable in one position to open said connecting means and render the small pistons effective to drive the shaft, means for shifting said valve device to close said connecting means and render said-large pistons effective, and means for relieving the pressure in the rod' ends of said cylinders whenthe motor is operating at low speed.

11. In a device of the character described, .a

casing comprising a motor block having a plurality of annularly arranged parallel cylinders formed therein, and a cylinder port opening through one face of the block to each of the cylinders, a section having fluid supply and exhaust passages formed therein andl an annular spacer interposed between said section and said motor block, one of vsaid passages communicating with the space formed between said motor block and said section through anV annular slot ing into the valve chamber radially inwardly of said cylinder ports, a `driven shaft rotatably mounted 'in the casing and having an eccentric stud lon, its innerv end for operating said valve, a plurality of low speed pistons in the head ends of said cylinders, a series of high vspeed pistons of smaller diameter slidably .mounted insaid as rods for said first mentioned pistons, awobble plate device forming a driving connection between said high speedpistons and said shaft and including an anti-friction bearing having concentric and inwardly of `said ports and the other of said passages communicating with said space adjacent the periphery of the space, and a disk-like valve having auid-tig'ht sliding fit in the space between said motor block and said section, an annular 'passage formed in said valve opening through both faces ofthe valve, said cylinders andV selectively operable as pistons orV nav - passage always being' incommunication with the annular slot andthe space beyond the periphery of the valve always being in communication with the other of said fluid passages, means for imparting to said valve an-eccentric motion whereby .the valve successively connects the ports alternately tothe supply 'and exhaust passage,

a plurality of low speed pistons in said cylinders, a series of pistons of smaller diameter .slidably mounted in said cylinders and selectively operable as pistons or as rods for said rst mentioned pistons, a wobble plate device forming a driving connection between said smaller' sized pistons and said shaft,` and control means for changing the speed of said driven shaft by rendering one set of pistons or the other effective to operate said wobble plate comprising means for alternatively connecting said cylinder ports to the opposite ends` of the cylinders.

12. A fluid motor comprising, in combination a casing, a ilrst series of piston and cylinder dcvices in said casing, av second series of smaller piston and cylinder devices in said casing, a`

driven shaft, a wobble plate secured to said shaft and operable by the pistons of said devices inders therein, a port for the head end of each 'of'` the pistons, and means for adjusting the shan .t combination, a casing, a shaft'rotatably mounted in said casing, means for rotating said shaft comprising a plurality of piston and cylinder devices arranged annularly about said shaft/nd means connecting the pistons thereof to drive the shaft, and means-for controlling the ow of uid to and from said pistons including a tubular valve device Vslidably mounted in said casing and surrounding said shaft operable in one position to effect operation of' said shaft at one speed and operable in another position to effect .operation of said shaft at another speed.

cylinder and a valve chamber, a valve slidably v mounted in the valve chamber for eccentric movement over the ends of said ports, inlet ports opening into the valve chamber to one side of the cylinder ports and outlet ports opening into the valve chamber to the other side of said cylinderports, a driven shaft rotatably mountedin the casing, means driven thereby for giving an eccentric movement to said valve, a plurality of large pistons in said cylinders, a series of pistons of smaller diameter slidably mounted in A said cylinders and selectively operable to drive the shaft, means forming a driving connection between said pistons and said shaft, and control means for changing the speed of said driven shaft by rendering one set of pistons or both sets of pistons eifective to operate said shaft.

14. A multi-speed fluid motor comprising, in combination, a casing, a plurality of pistons, a

driven shaft, adjustable means connecting the pistons to drive said shaft, means for conducting uid ,to and from said pistons including a 16. A two-speed fluid motor comprising, in

combination,` a casing, a shaft extending longi- A tudinally of said casing, a plurality of cylinders extending longitudinally of the casing and arranged about the shaft parallel therewith, pistons reciprocable in said cylinders including low speed and .high speed pistons, a wobble plate for converting the reciprocatory movement of said pistons into rotary movement of said shaft, and means for conducting pressure uid to vand from saidl cylinders operable alternatively to effect operationof said shaft at a low speed or to effect operation of said high speed pistons only, said low speed pistons remaining stationary, to driveV said shaft at a higher speed. y

17. A two-speed fluid mottlor comprising, in combination, a casing, a sha t extending longitudinally of saidY casing, a rst annular series of cylinders formed in said casing surrounding/.saidshaft, a second annular series of smaller cyli-nders formed in said casing, fluid supply and exhaust ports in said casing, a port leading to control device operable in one position to effect f operation ofcertainfof the pistons and operable 'in another position to effect operation of other 4both sets of piston and cylinder devices eective to drive said shaft.A

GUNNAR A. WArmMARK. 

